Abstract

Amorphous semiconducting materials have unique electrical properties that may be beneficial
in nanoelectronics, such as low leakage current, charge memory effects, and hysteresis
functionality. However, electrical characteristics between different or neighboring
regions in the same amorphous nanostructure may differ greatly. In this work, the
bulk and surface local charge carrier transport properties of a-TaNx amorphous thin films deposited in two different substrates are investigated by conductive
atomic force microscopy. The nitride films are grown either on Au (100) or Si [100]
substrates by pulsed laser deposition at 157 nm in nitrogen environment. For the a-TaNx films deposited on Au, it is found that they display a negligible leakage current
until a high bias voltage is reached. On the contrary, a much lower threshold voltage
for the leakage current and a lower total resistance is observed for the a-TaNx film deposited on the Si substrate. Furthermore, I-V characteristics of the a-TaNx film deposited on Au show significant hysteresis effects for both polarities of bias
voltage, while for the film deposited on Si hysteresis, effects appear only for positive
bias voltage, suggesting that with the usage of the appropriate substrate, the a-TaNx nanodomains may have potential use as charge memory devices.